Confidential data are usually encrypted if they are intended to be transmitted via an untrustworthy transmission medium.
Various encryption apparatuses are known from the prior art. The Advanced Encryption Standard (AES) is a symmetrical cryptosystem whose algorithm is freely available. The key used for AES encryption must be available to the recipient of the data in order to be able to decrypt the data.
AES is considered to be secure nowadays; on account of the developments in the field of encryption techniques, it can be assumed that, in approximately 30 years, data encrypted with AES will be able to be decrypted by unauthorized persons who do not have the required key.
When transmitting the data via a transmission medium, for example the Internet, data pass through a plurality of nodes before they arrive at the recipient. A node can have a long-term memory and can store forwarded messages. For confidential messages which have been encrypted, this means that they cannot be directly decrypted by unauthorized persons; however, it is not possible to guarantee that the data will not be able to be decrypted by unauthorized persons even after a relatively long period of time, for example in 30 years.